In this paper, the effects of fiber content on the mechanical properties and the interlaminar fracture toughness of glass fiber reinforced epoxy composites using cyanethyldiethylenetriamine hardner have been investigated. The lamellar composites were fabricated with different fiber weight contents (68.2 percent, 61.4 percent, 52.1 percent and 4?7 percent) by using hand lay-up method. The interlaminar fracture toughness of the composites has been studied under mode I (DCB) loading condition. The fracture energy is deduced from the data according to the modified compliance calibration (MCC) method. Results show that the mode.71 interlamilar fracture toughness for crack initiation, GIG were decreased gradually with increasing in fiber content. The fracture surfaces of the specimens were observed by scanning electron microscopy, and the fracture mechanism was analysed.